SOLVED "Object reference not set to an instance of an object." Getting this error message in SimPe after fixing integrity while trying to make a custom accessory

I've making custom accessories in the sims 2 for quite some time and i never had this problem until know.
When I first create the custom package in SimPe, and after i save it and do the 'fix integrity' stage, it gives me this error message that says "object reference not set to an instance of an object"

what's going on? and can someone please tell me how i can fix it?
please help <3

i copied the whole thing here:

Message:
Object reference not set to an instance of an object. SimPE Version:
Default (0.73.44.37511).

Exception Stack:
System.NullReferenceException: Object reference not set to an instance of an object.
at pjse.FileTable.Remove(Entry key)
at pjse.FileTable.PFD_DescriptionChanged(Object sender, EventArgs e)
at System.EventHandler.Invoke(Object sender, EventArgs e)
at SimPe.Packages.PackedFileDescriptor.DescriptionChangedFkt()
at SimPe.Packages.PackedFileDescriptorSimple.set_Instance(UInt32 value)
at SimPe.Plugin.FixObject.Fix(Hashtable map, Boolean uniquefamily)
at SimPe.Plugin.FixTool.ShowDialog(IPackedFileDescriptor& pfd, IPackageFile& package)